However, in Alzheimer’s disease (AD) dysfunction of enzymes that are responsible for phosphorylating tau, such as glycogen synthase kinase-3, gives rise to a hyperphosphorylated version of the protein that aggregates and forms insoluble intracellular tau neurofibrillary tangles (NFTs) (Iqbal et al. 2016). This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.